Update search to default to multithreaded.

Author: larshg

search/include/pcl/search/search.h

@@ -396,14 +396,15 @@ namespace pcl
         }
 
         /** \brief Set the number of threads to use for searching over multiple points or indices
-         * \param[in] nr_threads the number of threads to use (0 automatically sets the threads based on the hardware)
+         *  \param[in] num_threads the number of threads to use (0 automatically sets the threads based on the hardware)
          */
-        void setNumberOfThreads(unsigned int nr_threads) {
+        void setNumberOfThreads(unsigned int num_threads) {
           #ifdef _OPENMP
-          num_threads_ = nr_threads != 0 ? nr_threads : omp_get_num_procs();
+          num_threads_ = num_threads != 0 ? num_threads : omp_get_num_procs();
           #else
           if (nr_threads != 1) {
-            PCL_WARN("OpenMP is not available. Keeping number of threads unchanged at 1\n");
+            PCL_WARN("OpenMP is not available. Setting number of threads to 1\n");
+            num_threads_ = 1;
           }
           #endif
         }
@@ -418,7 +419,7 @@ namespace pcl
         std::string name_;
 
         /** \brief The number of threads to use when searching over multiple points or indices */
-        unsigned int num_threads_{1};
+        unsigned int num_threads_{0};
 
       private:
         struct Compare